Improvement in blackboards



UNITED STATES PATENT OFFICE.

FRANK G. JOHNSON, OF NEW YORK, N. Y.

IMPROVEMENT IN BLACKBOARDS.

Specification forming part of Letters Patent No. 133,583, dated December 3, 1872.

To all whom it may concern:

Be it known that I, FRANK G. J OHNSON, of

the city of New York, in the county and State of New York, have invented a new and useful Improvement in Tablet-Blackboards, of which the following is a specification:

This invention relates to a new and useful improvement in blackboards for schools and for all the purposes for which the ordinary blackboard is used; and it consists in a series of slates or tablets and in a grooved frame or case, in which grooves the tablets slide, the construction and arrangement being as hereinafter more fully described.

In the accompanying drawing, Figure 1 represents a front view of the improved blackboard; Fig. 2 is a longitudinal section of Fig. 1 taken on the line as m and the line y y of Fig. 3; and Fig. 3 is an end view.

Similar letters of reference indicate corresponding parts.

A-represents the case, and B the tablets. The case consists of two pieces of wood, 0 and D, of a length about equal to the tablets, and with grooves in the inner side thereof made by inserting thin strips of wood or by plowing the pieces, as may be found advisable. These pieces are connected together by the crossbars E E, which are secured to the back edges of the pieces 0 D, the ends of which bars project above and below, with stays or brackets H applied, as seen in Fig. 3, to one or both of the pieces 0 D, for the purpose of keeping them at right angles with the bars, as seen in Fig. 3. F represents the grooves, of which there may be more or less in number. When five (more or less) tablets are combined in the case they require no more wall-space than a single one. A problem may be demonstrated on the outside of the first tablet; and it may be turned over and the other side used; or it may be drawn out so as to expose another tablet and laid away, or drawn in either direction so as to expose the next tablet or a part of it, and still remain in the case; and so of all the tablets. The case is designed to hang upon the wall, as indicated by the holes G G, but'it may be supported in any manner.

Blackboards as usually constructed are very bulky and cumbersome, and the demonstrations thereon cannot be preserved; or if allowed to remain they are apt to confuse the pupil. By my arrangement each problem may be demonstrated on a separate tablet, and

preserved as long as may be required.

Having thus described my invention, I claim and desire to secure by Letters Patent- The improved educational device composed of the case formed of the longitudinallygrooved bars or plates 0 and D, secured to vertical suspension-bars E, and the sliding tablets B B, all as shown and described.

FRANK Gr. JOHNSON.

Witnesses:

O. SEDGWICK, ALEX. F. ROBERTS. 

